This invention relates to a multiple-stage adsorption separator and, particularly, to a multiple-stage adsorption separator suitable for use as a multiple-stage adsorption separator with simulated moving-beds.
For the separation of a mixture which is difficult to separate by distillation, a multiple-stage adsorption separating process of a simulated moving-bed system is known. In this separating process, four operations: a desorption operation, a concentration operation, an adsorption operation and recovery of the adsorbent are performed continuously and simultaneously. Such adsorption separating technique with the simulated moving-beds is applied to, for example, the separation of a mixture of xylene isomers (Japanese Published Patent Application (Kokoku) No. 42-15681, Japanese Published Patent Application (Kokoku No. 5010517), the separation of diisopropyl naphthalenes (Japanese Published Unexamined Patent Application (Kokai) No. 2-172929) and the like. FIG. 1 shows a diagram explaining the principle of adsorption separating with the simulated moving-bed system. In this Figure, the reference numerals 1-6 designate adsorption chambers having adsorbent packed beds and these chambers are mutually connected. The reference numeral 17 designates an adsorbent feed line, the reference numeral 18 designates an extract withdrawing line, the reference numeral 19 designates a feedstock feed line, the reference numeral 20 designates a raffinate withdrawing line and the reference numeral 21 designates a recycle line. The reference numeral 22 designates a pump. In the arrangement of the adsorption chamber 1-16 and the lines 17-21 as shown in FIG. 1, the desorption operation is first performed in the adsorption chambers 1-3, the concentration operation is performed in the adsorption chambers 4-8, the adsorption operation is performed in the adsorption chambers 9-13 and the recovery of the adsorbent is performed in the adsorption chambers 14-16.
In such multiple-stage adsorptive separation with the simulated moving-bed-system, each of the feed and withdrawing lines is shifted in the liquid flow direction by one chamber with valve control at a predetermined time interval. Therefore, in the next time interval, the desorption operation is performed in the adsorption chamber 2-4, the concentration operation is performed in the adsorption chamber 59, the adsorption operation is performed in the adsorption chamber 10-14 and the recovery of the adsorbent is performed in the adsorption chamber 15-1. Such an operation is continuously performed so that the adsorption separating process simulation moving-bed system for a fluid mixture can be attained.
An apparatus used for the above multiple-stage adsorption separating process of the simulated moving-bed system comprises the connected adsorbent packed beds. In order to carry out this adsorptive separation efficiently and economically, the development of the apparatus is an important, technical subject. The apparatus of this kind generally comprises the multiple adsorbent packed vessels connected sequentially through manifolds. However, in the case of this apparatus, since the multiple adsorbent packed vessels formed individually are used, equipment efficiency is low and equipment cost is increased, further pressure drop and heat loss of the fluid passing through the manifolds are large and, thus, the apparatus can not be considered industrially advantageous.
Japanese Published Unexamined Patent Application (Kokai) No. 58-79534, shows an adsorbent separator which comprises a multiplicity of adsorbent packed beds arranged so as to define multiple-stages in a large, cylindrical vessel. However, in the case of this apparatus, due to the complicated arrangement of the adsorbent packed beds, it is difficult to arranged the adsorbent packed beds and their packing requires a long time and, further, it is troublesome to change the adsorbents. Finally, this separator has the disadvantage point of high equipment cost.